A concentration of milk to one-fifth volume is normal in the production of khoa. Khoa is used as the base for a wide variety of Indian sweets. About 600,000 metric tons is produced annually in India. Khoa is made from both cow and water buffalo milk.
Khoa is normally white or pale yellow. Khoa prepared in the winter may be saved for use in the summer and may acquire a green tinge and grainier texture from a surface mould. This is called hariyali (green khoya) and is used to make gulab jamun.
Khoa is made by simmering milk in an iron karahi for several hours, over a medium fire. The gradual vaporization of its water content leaves coagulated solids in milk, which is khoa. 175–180°F (about 80°C) is ideal temperature to avoid boiling and to minimize scorching. Other quick way of making khoa is to continue mixing full fat milk powder to skimmed milk until it becomes khoa.
Khoya is used in various types of sweets such as pedha (penda in Gujarati), barfi(or burfi) and halwa.
- Pedha is sweetened khoya formed into balls or thick disks (like patties) with flavoring such as Saffron and/or Cardamom added.
- Barfi is also flavoured. However, khoya is not the only ingredient. Typically another ingredient such as thickened fruit pulp or coconut shavings are added to khoya and slow cooked until the moisture evaporates sufficiently to give the consistency of fudge, so that it can be flattened and cut into rectangles, parallelograms or diamond shapes.
- Halwa is essentially a fudge made by adding khoya to give a dairy-like taste and texture and as a thickening agent.